We have a dataguard setup with primary database on 10.2.0.3 on AIX. I have kept all the parameters same in parameter file but querying SHOW SGA gives different results on primary database and DR database which causes ORA-04030 - Out of memory error. Can you please suggest some guidance?

because on DR site there are no sql running so size of buffer cache remain big in productioon site.....
the variable component of the SGA the sum of the "named" pools -- large pool, java pool
and shared pool. as there are no DML running these pools are also not utilizing more space....